376 NETHER LOCH ABE R. 



and at the suggestion of his friend the distinguished Arago, 

 Leverrier undertook to answer it, and in due time did answer it in 

 such wise as filled the world with astonishment and admiration. 

 Resolutely grasping with his task, Leverrier laboured long and 

 laboured hard to resolve the mystery, and as a first step with this 

 result, that the problem was utterly unresolvable on any other 

 conceivable theory or conjecture than that another planet, albeit 

 unknown to astronomers, and hitherto as unsuspected as it was 

 unseen, existed exterior to "Uranus, and that it was to the attraction 

 or disturbing influence of this hitherto undreamt-of orb that the 

 perturbations and mysterious vagaries of Uranus could alone be 

 ascribed. A memoir stating the conclusion arrived at, and all the 

 calculations leading towards it, was read before the Royal Academy 

 of Sciences in June 1846, and the young and daring astronomer 

 straightway resumed his labours, of which the aim was now to 

 determine the elements of the orbit of the unknown planet, in the 

 existence of which he now believed as firmly as in that of the 

 visibly perturbed orb Uranus itself. The astronomical world 

 shook its head dubiously, and waited. Did such a planet really 

 exist, and if it did, could this daring Frenchman find it] M. 

 Leverrier meantime laboured on, and finally mastering every diffi- 

 culty, he gave the computed plans of orbit, the mass and natural 

 position of his constructed world, if in truth, that is, such a 

 world existed. This was in a second memoir to the Academy of 

 Sciences on the last day of August 1846. Towards the end of 

 the following month (September 1846), Leverrier wrote to M. 

 Galle, of Berlin, requesting him to level the powerful telescope 

 under his charge at a particular point of the heavens, and there, in 

 effect, said the wonderful Frenchman, you will find the cause 

 of the perturbations of Uranus, a new and distant world, hitherto 

 undreamt of and unseen by mortal eye, but existing all the 

 same. M. Galle, on the first favourable opportunity, directed his 



